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tpm: ibmvtpm: Avoid error message when process gets signal while waiting

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When rngd is run as root then lots of these types of message will appear
in the kernel log if the TPM has been configured to provide random bytes:

[ 7406.275163] tpm tpm0: tpm_transmit: tpm_recv: error -4

The issue is caused by the following call that is interrupted while
waiting for the TPM's response.

sig = wait_event_interruptible(ibmvtpm->wq, !ibmvtpm->tpm_processing_cmd);

Rather than waiting for the response in the low level driver, have it use
the polling loop in tpm_try_transmit() that uses a command's duration to
poll until a result has been returned by the TPM, thus ending when the
timeout has occurred but not responding to signals and ctrl-c anymore. To
stay in this polling loop extend tpm_ibmvtpm_status() to return
'true' for as long as the vTPM is indicated as being busy in
tpm_processing_cmd. Since the loop requires the TPM's timeouts, get them
now using tpm_get_timeouts() after setting the TPM2 version flag on the
chip.

To recreat the resolved issue start rngd like this:

sudo rngd -r /dev/hwrng -t
sudo rngd -r /dev/tpm0 -t

Link: https://bugzilla.redhat.com/show_bug.cgi?id=1981473
Fixes: 6674ff145e ("tpm_ibmvtpm: properly handle interrupted packet receptions")
Cc: Nayna Jain <nayna@linux.ibm.com>
Cc: George Wilson <gcwilson@linux.ibm.com>
Reported-by: Nageswara R Sastry <rnsastry@linux.ibm.com>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Tested-by: Nageswara R Sastry <rnsastry@linux.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
This commit is contained in:
Stefan Berger 2021-08-12 22:45:48 +03:00 committed by Jarkko Sakkinen
parent a4aed36ed5
commit 047d4226b0
2 changed files with 16 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
drivers/char/tpm/tpm_ibmvtpm.c
View File

@ -106,17 +106,12 @@ static int tpm_ibmvtpm_recv(struct tpm_chip *chip, u8 *buf, size_t count)
{
struct ibmvtpm_dev *ibmvtpm = dev_get_drvdata(&chip->dev);
u16 len;
int sig;
if (!ibmvtpm->rtce_buf) {
dev_err(ibmvtpm->dev, "ibmvtpm device is not ready\n");
return 0;
}
sig = wait_event_interruptible(ibmvtpm->wq, !ibmvtpm->tpm_processing_cmd);
if (sig)
return -EINTR;
len = ibmvtpm->res_len;
if (count < len) {
@ -237,7 +232,7 @@ static int tpm_ibmvtpm_send(struct tpm_chip *chip, u8 *buf, size_t count)
* set the processing flag before the Hcall, since we may get the
* result (interrupt) before even being able to check rc.
*/
ibmvtpm->tpm_processing_cmd = true;
ibmvtpm->tpm_processing_cmd = 1;
again:
rc = ibmvtpm_send_crq(ibmvtpm->vdev,
@ -255,7 +250,7 @@ again:
goto again;
}
dev_err(ibmvtpm->dev, "tpm_ibmvtpm_send failed rc=%d\n", rc);
ibmvtpm->tpm_processing_cmd = false;
ibmvtpm->tpm_processing_cmd = 0;
}
spin_unlock(&ibmvtpm->rtce_lock);
@ -269,7 +264,9 @@ static void tpm_ibmvtpm_cancel(struct tpm_chip *chip)
static u8 tpm_ibmvtpm_status(struct tpm_chip *chip)
{
return 0;
struct ibmvtpm_dev *ibmvtpm = dev_get_drvdata(&chip->dev);
return ibmvtpm->tpm_processing_cmd;
}
/**
@ -457,7 +454,7 @@ static const struct tpm_class_ops tpm_ibmvtpm = {
.send = tpm_ibmvtpm_send,
.cancel = tpm_ibmvtpm_cancel,
.status = tpm_ibmvtpm_status,
.req_complete_mask = 0,
.req_complete_mask = 1,
.req_complete_val = 0,
.req_canceled = tpm_ibmvtpm_req_canceled,
};
@ -550,7 +547,7 @@ static void ibmvtpm_crq_process(struct ibmvtpm_crq *crq,
case VTPM_TPM_COMMAND_RES:
/* len of the data in rtce buffer */
ibmvtpm->res_len = be16_to_cpu(crq->len);
ibmvtpm->tpm_processing_cmd = false;
ibmvtpm->tpm_processing_cmd = 0;
wake_up_interruptible(&ibmvtpm->wq);
return;
default:
@ -688,8 +685,15 @@ static int tpm_ibmvtpm_probe(struct vio_dev *vio_dev,
goto init_irq_cleanup;
}
if (!strcmp(id->compat, "IBM,vtpm20")) {
if (!strcmp(id->compat, "IBM,vtpm20"))
chip->flags |= TPM_CHIP_FLAG_TPM2;
rc = tpm_get_timeouts(chip);
if (rc)
goto init_irq_cleanup;
if (chip->flags & TPM_CHIP_FLAG_TPM2) {
rc = tpm2_get_cc_attrs_tbl(chip);
if (rc)
goto init_irq_cleanup;

2
drivers/char/tpm/tpm_ibmvtpm.h
View File

@ -41,7 +41,7 @@ struct ibmvtpm_dev {
wait_queue_head_t wq;
u16 res_len;
u32 vtpm_version;
bool tpm_processing_cmd;
u8 tpm_processing_cmd;
};
#define CRQ_RES_BUF_SIZE PAGE_SIZE